1. Field of the Invention
The present invention relates to a honeycomb structure, and more particularly, it relates to a honeycomb structure whose volume resistivity is in a predetermined range and which is a catalyst support and also functions as a heater.
2. Description of Related Art
Heretofore, a honeycomb structure made of cordierite and including a loaded catalyst has been used in a treatment of a harmful substance in an exhaust gas discharged from a car engine. It is also known that a honeycomb structure formed by a silicon carbide sintered body is used in the purification of the exhaust gas (e.g., see Patent Document 1).
When the exhaust gas is treated by the catalyst loaded onto the honeycomb structure, it is necessary to raise a temperature of the catalyst to a predetermined temperature. However, at the start of an engine, the catalyst temperature is low, and hence there has been a problem that the exhaust gas is not sufficiently purified.
Therefore, a method has been investigated in which a heater made of a metal is installed on an upstream side of a honeycomb structure including a loaded catalyst, to raise a temperature of an exhaust gas (e.g., see Patent Document 2).